Mack Gas Engines ?!?!?

[HK Trucking]

I bet them Gas engined Mack's are nicer to drive no splitting. . .just clutch n shift maybe even shift no clutch

The purpose of having the aux trans in there is to allow the driver to split shift as necessary to keep the engine in it's proper operating range, be it a gas or diesel engine.

Splitting the Thermodyne so you didn't split the Thermodyne stick your arms threw the steering wheel and start grabbing gear, hoping you never hit neutral on both sticks at the same

Mike

Actually, having both sticks hit neutral at the same time is not a problem, and is actually necessary for true 2 hand shifts. The key is to use the proper technique and timing so you don't "hang out" in double neutral too long. You gotta know what to do,and get 'er done quickly and smoothly. When that is accomplished, a quad box can be shifted as smoothly as an automatic, and the engine will always remain in its proper operating range the way that setup was designed to work.

[B61TENDT711]

I got told many horror stories about if you lugged a thermodyne it blew head gaskets and if you hit double neutral and you couldn't get one or the other back in gear at the right time you would have to come to a complete stop and start over.

Mike

[HK Trucking]

I got told many horror stories about if you lugged a thermodyne it blew head gaskets

That is correct, and it would burn holes in the pistons eventually too if lugged too often or too long.

and if you hit double neutral and you couldn't get one or the other back in gear at the right time you would have to come to a complete stop and start over.

Mike

That's why I said in the previous post "The key is to use the proper technique and timing so you don't "hang out" in double neutral too long. You gotta know what to do,and get 'er done quickly and smoothly"

I can honestly say that even when I was a kid, learning how to do this stuff, I never had to come to a stop and start over due to a missed shift. There is always a way to get back in gear as long as you go for a gear that corresponds to the current road speed and engine RPM.

.

[Speed]

I've been having trouble with the "smoothly" part of the program,which I've narrowed down to:

The wrong lube in the secondary box.

Maladjusted,loose,badly aligned linkage on the secondary box.

Possibly a shortage of coordination at the shift knob end of the shifters.

I still maintain that part of it is in how quickly this engine picks up and drops rpm's,leaving a significantly narrower "window" to make a clean shift. Maybe if I change the leverage ratio to require a little more gas pedal travel to reach full throttle,I could make the engine speed a little more controllable.

Or,maybe I just need to squirrel up the money to license,insure and fuel the truck and just drive it full time for a while,hopefully get used to it and get better with the "smoother" part of the program.

Speed

[B61TENDT711]

That is correct, and it would burn holes in the pistons eventually too if lugged too often or too long.

That's why I said in the previous post "The key is to use the proper technique and timing so you don't "hang out" in double neutral too long. You gotta know what to do,and get 'er done quickly and smoothly"

I can honestly say that even when I was a kid, learning how to do this stuff, I never had to come to a stop and start over due to a missed shift. There is always a way to get back in gear as long as you go for a gear that corresponds to the current road speed and engine RPM.

.

If you'll also notice I said "i heard horror stories of" i heard all of the what not to do's and i sat back and watched few different guys shift these trucks before i bought one myself as to not damage it.

Not point in buying a Rig you can't drive right ?

Mike

[B61TENDT711]

I've been having trouble with the "smoothly" part of the program,which I've narrowed down to:

The wrong lube in the secondary box.

Maladjusted,loose,badly aligned linkage on the secondary box.

Possibly a shortage of coordination at the shift knob end of the shifters.

I still maintain that part of it is in how quickly this engine picks up and drops rpm's,leaving a significantly narrower "window" to make a clean shift. Maybe if I change the leverage ratio to require a little more gas pedal travel to reach full throttle,I could make the engine speed a little more controllable.

Or,maybe I just need to squirrel up the money to license,insure and fuel the truck and just drive it full time for a while,hopefully get used to it and get better with the "smoother" part of the program.

Speed

i watched many other guys drive these before i bought mine, but yes once i got it i drove it every place to work to the store out to eat every place i went it went for about 4 or 5months. . .

Most young guys get confused on a 5spd car or pickup truck i take some pride in being a young lad of 27 that can drive 2 stick Mack rather well i skill i learned at age 19.

Mike

[Pete]

There were some B42's in Canada that had Chrysler (Dodge) truck 413 V8's.A friend of mine had one,he bought it used around 63 or 64.I think it was 2 or 3 years old when he bought it.

Pete

[Speed]

There were some B42's in Canada that had Chrysler (Dodge) truck 413 V8's.A friend of mine had one,he bought it used around 63 or 64.I think it was 2 or 3 years old when he bought it.

Pete

I really like the Dodge 413,and the 383 too. seems like they have the big block torque,but they rev like a small block-best of both worlds. Getting scarce these days though.

This subject makes me wonder how politically incorrect it'd be for me to use a 413 in my E model if the EN354 ever breaks.....

Speed

[Packer]

My 'B-421' came with a 401-2 cid. gas engine and a "Baby" quadraplex!

Split shifting all the way!!!

The baby quad has the aux. tranmission on the RIGHT side instead of the left.

Tends to make you loose your place when splitting!!!! LOL

Packer

[B61TENDT711]

401-2? care to enlighten me ?

for some reason i always seem to use the clutch in the 2 stick transmissioned truck but any of the single stick unit i clutch 1st gear and i clutch reverse and shift the rest with out it. . .

Mike

[Speed]

401-2? care to enlighten me ?

for some reason i always seem to use the clutch in the 2 stick transmissioned truck but any of the single stick unit i clutch 1st gear and i clutch reverse and shift the rest with out it. . .

Mike

I've been "half-double-clutching" my trucks for years,ever since my '51 Ford F-5's 4 speed "crash-box";I bring it up to shifting speed,pull it out of gear,then hit the clutch and shoot the next gear. Downshifting,same general idea;bring it down to shifting speed,knock it out of gear,rev the engine to about the right rpm for the shift,then hit the clutch and slide it into gear. Half the motion and gets the same result as double clutching. Probably not the best way to shift,but it works and I've never broke anything so I guess it's okay.

BTW,Packer-just looking in my book it appears the Mono-shift is a direct 5th transmission,so it'd be more gears,but same speed/rpm's. They DID offer a straight 5 speed that was Overdrive 5th. (I wonder if the Bus 5 speed is an overdrive??)

Speed

[B61TENDT711]

According to the Rpm + tire size + mph i got about a .70 OD in the 15spd. . .

5spd-OD n 3spd-OD ? . . . 5spd w/ 5th .85:1 + 3spd 3rd .85:1 ?

.85-1.00 = .15x2 = .30 30% OD . . .

Edit:

I wounder if this whole bloody truck wasn't a customized build ?

711 Diesel with a turbo charger,2 stick 15spd with about .70 OD, 6.38 Gearing, and 12.00-24 tires . . .

Truck runs 65mph@2,000rpm which would require a 30% or .70 OD ratio.

Mike

[Speed]

According to the Rpm + tire size + mph i got about a .70 OD in the 15spd. . .

5spd-OD n 3spd-OD ? . . . 5spd w/ 5th .85:1 + 3spd 3rd .85:1 ?

.85-1.00 = .15x2 = .30 30% OD . . .

Edit:

I wounder if this whole bloody truck wasn't a customized build ?

711 Diesel with a turbo charger,2 stick 15spd with about .70 OD, 6.38 Gearing, and 12.00-24 tires . . .

Truck runs 65mph@2,000rpm which would require a 30% or .70 OD ratio.

Mike

Damn-it must be tough being able to get that kinda road speed at 2 grand. My ol' gas rig has a 6.86 rear,direct 5 speed,and I think,about a .84 or so over on the Brownie,and currently has 9.00-20's on it,soon to be 10.00R-20's. As near as I can figure it,the 10.00's will give me about 4 more inches of diameter,which should bring me to 45 mph at 2,000 rpms,or 57 mph at 2,500 rpms. If I could cruise at 2,900 r's,I'd be able to match your 65 mph,but I don't see that being an option,at least not for very long.

Speed

[B61TENDT711]

Most Gasser's of the time period normally have a cruising range of 2900-3100rpm, from what i was told tho they were designed to run 2800-3200rpm, but its been my exp they run there best floating between 2900-3100rpm. . .

Edit:

you also have to remember them 12.00-24/12.00R24's are about 50" tall.

i would go from the 9.00-20's to 11.00-20's ,myself that's is what i did to my Studebaker M275Gasser its runs 66mph instead of only doing 55mph.

Mike

[fauthpk]

I have a B20 Mack with a en 291 gas engine. Engine was built by mack. Gas flat heads are the following, en 291, 330, 401, then they went to overhead valves. If i remember correctly mack used the same block for their gas and diesel engines. Diesels were called thermodynes.

[fxfymn]

Mack used gas engines in their fire trucks exclusively until 1960 and delivered their last gas powered fire truck in 1973. In addition to the 707 they produced the L head ENF 331, ENF 377; and the overhead ENF 510 and ENF 611 Thermodyne engines. There were also several other Mack produced gas engines used in earlier rigs.

All fire apparatus was delivered with dual ignitions since ignition failure the most likely reason for an engine to fail to start providing the battery was properly charged.

[sal]

we have a 1945 eh with a flat head 6 it has been in our family from new it was stamped by the war department and it gas with air brakes

[Vladislav]

we have a 1945 eh with a flat head 6 it has been in our family from new it was stamped by the war department and it gas with air brakes

Interesting to learn more about your EH. Was it originaly painted Olive drab or any commercial color?

I have army NM with 707 military version EY engine. It's mono ignition overhead thermodyne engine. And it has Mack 5 speed direct top box without any splitter. Tyres are 10.00-22 but it's the army truck with low road speed. Ratio is about 7.33 though with Timken-Detroit military pattern all wheel drive.

Vlad.

[Billy J]

I have a B-42 with an en401 gas engine they later made a few modifications and came out with the en402 (inline 6)

[Maddog13407]

only modification betweeen a 401 and 402 is 2 more head bolts in the corners of the head. everything else was the same. after a while you couldnt get 401 heads and many of my grandfathers 401's have 402 heads with an open hole. there were many variations and most of the B421's didnt have oil coolers on the block and had the cheap timing cover front mounts and the channel iron front motor frame mount instead of the heavier cast i beam saddle mount of the b42's. most B421's also had a single frame with fish plates , ''backbreaker'' 3 leaf walkin beam rears instead of Camelbacks and one fuel tank. there are variations with Mack as we scrapped a B421 that had a heavy FA517 front axle instead of a lighter one. believe the 291,331, 401 and 402 were all Continental design engines. think the only real Mack gassers were the overhead valve Thermodynes

[REOGasMackDiesel]

Wow lots of good Mack gasser info here.

Mike

[Trent]

 

I did a few dozen google n yahoo and even ask searches i can not find anything dealing with or related to Mack Gas engines.

I was chatting with a friend and even he don't even remember seeing a mack powered by nothing other then a Diesel engine.

Was there no such things as a Mack Gasser?

Mike

Yes the 707, it is very similar to the 673.  It had an overhead valve train and some had dual spark plugs with dual ignition.

[Mickleborough]

I have just bought a1956 B-42 Mack with a 6 cylinder gas engine. Need help in finding out what kind it is. New to this.

[Maddog13407]

401 flathead continental if its original. says Mack on block but was Continentals design

[Quentin Maver]

I have a 1941 Mack Fire Truck with 6 cyl gas engine. ( engine #358GB33A or 358GB88A) Looking for parts

please email qmm61750@aol.com or Like me on facebook Quentin Maver then PM me